Draft: rtpmanager: add support for RFC8843 (mid) and RFC8852 (rid) RTP header extensions

commit d6cf9a36

test: add tests for sdes-based RTP header extensions

mid, stream id and repaired stream id.

commit 389155ba

rtpmanager: add support for RFC8852 (rid) RTP header extensions

Both for regular RID and for adding on a repaired (RTX) etc stream.

commit 233ca9c4

rtpmanager: add support for writing RFC8843 (BUNDLE mid) RTP header extension

Requires gst-plugins-base!1259 (closed) to write the correct information into the RTP packets.